SWALLOWS 503 



these swallows appeared over the meadows, where they alternately skimmed 

 low and mounted almost out of sight, chasing one another, and giving their 

 twittering notes which sounded faintly or loudly according to the distance 

 of the birds from the observer. Probably the cloud formation over the 

 Valley, preceding the shower, had forced the birds down from the upper 

 air where they had been foraging. 



EouGH-wiNGED SwALLow. Stelgidoptcryx serripennis (Audubon) 



Field characters. — Body size about that of Linnet or Junco ; tail almost square-ended. 

 Whole upper surface dull brown; throat and chest grayish brown; belly and feathers 

 below base of tail white. No brilliant or iridescent markings whatsoever. Voice : Three 

 or four weak notes, zeetle-tzeet, repeated at irregular intervals. 



Occurrence. — Sparse summer visitant in foothills west of Sierra Nevada. Observed 

 by us only at following points: 2 miles southwest of Lagrange, on Blacks Creek west 

 of Coulterville, and near Bower Cave. Eecorded once in Yosemite Valley, May 22, 1903 

 (Widmann, 1904, p. 70), when two were seen over Sentinel Meadow in company with 

 Violet-green Swallows. Frequents vicinity of gulches having steep earth banks. In 

 pairs or small companies. 



The Eough-winged Swallow is the most local in its manner of occurrence 

 of the several species of swallows found in the Yosemite section. Previous 

 to 1919 it escaped our attention entirely, and subsequently was found 

 at only three places in the western foothills, as noted above. The species 

 differs from all of our other swallows as regards nesting site. It chooses 

 a steep earth bank and there digs a horizontal tunnel in which to place 

 its nest. There its spotless, white eggs and later the young are entirely 

 hidden from view. 



At Blacks Creek, one mile west of Coulterville, eight Rough-winged 

 Swallows were seen on the morning of May 10, 1919. There were suitable 

 nesting sites close by but the birds seemed not as yet to have settled down 

 for the rearing of broods. They were flying about, sometimes coming to 

 rest on dead weed tips or bare branches of trees; at times they alighted 

 directly on the dry sandy earth of a cow trail. 



From time to time the males were seen in pursuit of the females and, 

 while so engaged, to make rather striking use of their seemingly plain 

 garb. They would spread the long white feathers (under tail coverts) 

 at the lower base of the tail until these curled up along either side of the 

 otherwise brownish tail. The effect produced was of white outer tail 

 feathers, such as those of the junco or the pipit. Males can by means of 

 this trick be distinguished from the females at a distance of fully 50 yards. 

 An examination of specimens in hand reveals the fact that the under tail 

 coverts of the males are broader and longer than those of the females. 



A nest of this swallow was found by Mr. Donald D. McLean on Jordan 

 Creek near Bower Cave on June 20, 1920. It consisted of a mass of dry 

 grass placed in an excavation in an earth bank and contained three eggs. 



